Residential Building Inspector B1Building Planning and Life SafetyHard
A residential building inspector is reviewing plans for a new single-family dwelling that includes a stairway. The plans indicate the stairway will have a uniform riser height. What is the maximum variation in riser height permitted between any two risers in the same flight of stairs?
- A1/4 inch
- B3/16 inch
- C1/8 inch
- D3/8 inch
Show answer & explanationAnswer & explanation
Correct answer: D. 3/8 inch
Uniformity in stair riser height is crucial for safety, preventing trips and falls. The IRC allows for a very small maximum variation between any two risers in a flight of stairs to maintain this uniformity. The maximum permitted variation is 3/8 inch.
Why the other options are wrong
- A. 1/4 inch is a common tolerance but not the maximum for riser height variation in the IRC.
- B. 3/16 inch is too tight and not the specified maximum variation for riser height.
- C. This is a common distractor, as 1/8 inch is the maximum variation for tread depth.
Stair Riser Height Variation
The maximum allowable difference in height between any two consecutive risers within a single flight of stairs, critical for pedestrian safety and preventing tripping hazards.
- Ensures consistent stepping rhythm.
- Prevents tripping hazards.
- Strictly regulated by building codes (IRC).
Memory trick: Riser's 'R' for 'Roughly' '3/8' is fine.